Comparison of the size of Sardinella caught by the industrial and artisanal sectors in Côte d'Ivoire.
Sardinella aurita
Samples were taken between September and December 1985 and between September and December 1986, for both fisheries, and from the Bassam and Jacqueville sectors (Figures 10 and 11). Catches of large size Sardinella aurita are generally indentical (class 1+ and 2+, fishes of 15–25 cm) and are dominant. However, some small fishes of the 0+ class (5–10 cm) are caught but only by the canoe fleet.
Sardinella maderensis
Similar samples were taken between September and December 1986 in the same sectors (Figure 12). It is noted that catches by the canoe fleet are made up mainly of small Sardinella maderensis (5–15 cm) in contrast to the sardinella fishing fleet which catches only large individuals (15–25 cm).
The conclusion as regards the size of fish is that there is a relative homogeneity between Sardinella aurita caught in the Abidjan sector by the two fisheries, which could be explained by the proximity of S. aurita stocks centred on Ghana, and that on the contrary, the sizes of S. maderensis caught in that same sector are very heterogenous. However, it is difficult to generalize this conclusion because of the extension of S. maderensis towards the western area of Côte d'Ivoire. A sampling survey is needed to confirm any such assumption.
Sardinella aurita
It was deemed necessary by the working group to use the same scale to present the size distribution of Sardinella aurita caught with the main gears (beach seine, Poli net, sardine net) used by these fleets. Unfortunately, there were no annual statistics on the size distribution for all of these gears. It was therefore decided to use the 1982 statistics which include data relative to beach seines and ring nets and also because 1982 is considered as a “normal” year (from the point of view of climate, and consequently of the fishing techniques of the two types of gear).
Size frequency data were taken from the tables presented in Appendix 4. For each gear, the annual values were used, the estimated weight of samples is calculated using the length-weight relationship (Appendix 7) as regards the beach seine and the Marchal relation (1974) for the ringnet. The total number of individuals was thus obtained, knowing total catches of Sardinella aurita per fishing gear in 1982 (190.7 t and 6 982.9 t for the beach seine and the ringnet respectively).
Data are given in Appendix 4 and size distribution in Figure 13 (where a clear difference can be seen between the two gears: 5–6 cm for the beach seine and 18 cm for the ringnet).
